led accepted any u16 and main.rs clamped to 0..=1000 with no feedback,
inconsistent with sidetone which rejects out-of-range at parse time.
Add a clap range validator (0..=1000) and drop the silent clamp, so
invalid input now fails loudly.
Further quality-audit follow-ups:
- remove dead BragiDevice::open() (no caller; binary uses open_with_verbose)
- add tests: led range validation, format_battery for all status
variants, waybar "unknown" class
Bump 0.1.2 -> 0.1.3.
Sync Cargo.toml to 0.1.2 and bring PKGBUILD up to date (was stale at
0.1.0): pin the git source to the release tag for reproducible builds
and install the LICENSE file.